In recent decades due to financial scandals, corporate governance has received special attention in the field of accounting. The transaction with related parties is of the usual features of current activities. So this study was to evaluate the effect of corporate governance quality index on limiting earning management using unusual transactions with related parties in 70 companies listed in Tehran Stock Exchange during the period 2010-2015. The results of the data analysis showed that corporate governance has significant effects on unusual transactions with related parties. This result shows the importance of corporate governance and efforts to improve it and help improve earning management.